Tool holder



F. PRETSCH.

TOOL 'HOLDER.

APPLICATION FILED m3. 4. 1920.

Patented Feb. 21,1922.

v NW4 4 7w 7%? a y I IIVVIJVTOR line 4--4 of PATENT FRANK PRETSCH, OF PHILADELPHIA, PENNSYLVANIA.

TOOL HOLDER.

Specification of Letters Patent.

Patented Feb. 21., 1922.

Application filed February 4, 1920. Serial No. 356,301.

To all 407mm it may concern:

Be it known that I, FRANK Pnn'rsori, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented new and useful Improvements in Tool Holders. of which the following is a specification.

My invention relates to a new and useful improvement in tool holders, and has for its object to provide an exceedingly simple and effective device of this character whereby a tool may be clamped in the tool holder adj acent the working portion of the tool.

Another object of my invention is to so construct a tool holder that tools very short in length may be clamped therein, the clamp being so constructed that a relatively long bearing surface is provided without interfering with the work on which the tool is being used.

A further object of my invention is to provide a chamber or chambers in the tool post for the reception of the tool one portion be ing rectangular and the other inverted V shaped.

lVith these ends in view, this invention consists in thedetails of construction and combination of elements hereinafter set forth and then specifically designated by the claims.

In order that those skilled in the art to which this invention appertains, may understand how to make and use the same, I will describe its construction in detail, referring by numerals to the accompanying drawing forming a part of this application, in which Fig. 1, is a lower edge view of the tool holder embodying my improvement, a portion of the tool post being broken away.

Fig. 2, is a side elevation thereof.

Fig. 3, is a front end view, a portion of the tool post and tool being shown in section.

Fig. 4:, is a section of the tool post at the F ig. 2.

Fig. 5. is a similar view at the line 5-5 of Fig. 2.

In carrying out my invention as here embodied. 2 represents a tool post which is formed from a suitable rectangular bar of metal having formed in its under edge a longitudinal rectangular groove 3 running from the forward end rearwardly to a point intermediate the ends of the tool post producing a relatively short groove, and from the inner end of this rectangular groove runs a longitudinal inverted V shaped groove 4 which may terminate short of the rear end of the too]. post or may run the entire balance of the length of said post and where the two differently shaped grooves meet is formed an end wall. 5 for the rectangular groove 3.

On this tool post is slidably and adj ustably mounted the clamp 6 which is preferably circular in cross section as plainly shown in Fig. 1 and has a vertical or longitudinal slot 7 formed therethrough of a width approximately equalling the thickness of the tool post so as to snugly fit the latter, but of slightly greater length than the height of said tool post so that a certain amount of vertical or longitudinal movement of the clamp may be had upon the tool post for clamping tools of different sizes, one tool be ing here shown in the tool holder and represented by the numeral 8. Through the upper end of the clamp 6 is threaded an adjusting screw 9 the inner end or nose of which engages the upper edge of'the tool post 2 and if found desirable the upper face of said tool post may be spotted or provided with a depression 10 to receive the inner end of the adjusting screw and position the clamp upon the tool post.

Because of the shape of the clamp when the slot 7 is formed therein the ends of the walls of said slot are set back of the faces of said clamp in the region of said slot both at the top and bottom thereof so that a relatively long bearing surface is provided for the tool 8 when clamped in position which will effectively prevent chattering of the tool also making it possible to clamp the tool in proximity to its working end, and the tool post will be relatively short thereby re- .ieving the strain upon the projecting end of the tool and reducing to a minimum'the possibility of the tool breaking.

It is to be particularly noted that the clamp contacts with the tool without any other object between them and likewise the tool contacts with a long bearing surface on the tool post whereas the adjusting screw engages the tool post on the edge opposite the position of the tool so that no protuberances are provided which might act as a fulcrum to permit the tool to swing about.

As the tools generally used with tool holders oi. this character are provided with diamond shaped shanks the inverted V shaped groove permits the use of such a tool when too long to be accommodated by the length of the groove 3, but when said tool is broken the short working end may be ground down so as to be rectangular in cross section of a size to fit the rectangular groove 3 after which it may be inserted in said groove and the clamp then tightened by the set screw 9 so as to securely hold the tool in place.

' Of course I do not wish to be limited to the exact details of construction as herein shown as these may be varied within the limits of the appended claims without departing from the spirit of my invention.

laving thus fully described my invention what 1 claim as new and useful is 1. In a tool holder, a tool post having a rectangular groove formed in its lower edge from its forward end inward to a point intermediate its ends and having another groove inverted V shaped in cross section and communicating with the inner end of said first named groove.

2. A tool holder including a tool post having a groove formed in one edge, of one shape throughout a portion of its length and of a difierent shape throughout the balance thereof.

In testimony whereof, I have hereunto atfixed my signature. 7

FRANK PRETSCH. 

